Aircraft propelling mechanism



Sepf. 22,- 1936. A, JA OBS 2,055,081

I AIRCRAFT PROPELLING MECHANISM Filed April 16, 1935 2 Sheets-Sheet lWITNESSES." filmrt b5 9 I '1 BY 7 Sept. 22, 1936. A. R. JACOBS AIRCRAFTPROPELLING MECHANISM Filed April 16, i955 2 Sheets-Sheet 2 TTORNEYS.

Patented Sept. 22, 1936 UNITED STATES PATENT OFFICE AIRCRAFT PROPELLINGMECHANISM Albert E. Jacobs, Beiffton, Pa. Application April 16, 1935,Serial No. 16,655

. 1 Claim.

This invention, while relating generally to improvements in aircraftpropelling mechanism, is

more particularly related to constant torque multiple speed transmissiongears for aircraft, which .5 provide a drive connectionbetween the powershaft and the propeller shaft.

The development in aircraft has so increased the top speed of the craftthat the pitch of the propeller has had to be increased to such an ex-10 tent that it is difficult to obtain suflicient revolutions of theengine in take-off and climb without some means of either varying thatpitch at will or being able to change the ratio between the speed of theengine and the speed of the propeller.

By providing a constant torque transmission in of a. preferredembodiment thereof which follows and which has reference to theaccompany- 40 ing drawings.

Of the drawings: Fig. I represents a longitudinal section of theconstant torque multiple speed transmission embodying this invention, asinstalled in the for- 45 ward end of an aeroplane.

Fig. II represents a cross-section of the apparatus, taken about thelines IIII of Fig. I.

In Fig. I the apparatus embodying my invention is shown housed in acasing l andcomprises 50 generally a power shaft 2,.a propeller shaft 3,

both of which are hollow, a conventional clutch 4 of the friction disctype joining the two shafts 2 and 3, a driving .gear' 5 formedintegrally on a sleeve 6 extended from the clutch 4, a set of clustergears I meshing with the driving gear 5 inside of the casing i.

(see Fig. II), a second set of cluster gears 3 axially connected to saidfirst set of gears 1. gear by gear, a driven gear 3 keyed to thepropeller shaft 3 and in mesh with the set of gears 3, and finally anover-riding clutch mechanism Ill fitted 6 into each gear H of the set ofgears I.

The casing I, of a conventional type having a number of integralextensions inward to support parts of the mechanism, has a cover-platel6 over the tapered end nearest the propeller. The 10 cover-plate I3 isbolted to the casing I and cooperates in protecting the mechanism in thecasing I from dirt, with a retaining sleeve l'l threaded onto thepropeller shaft 3 and drawn up tight against a locking ring IS. Thelocking ring l9 has an apron which. is bent outward to cooperate withthe plate l6 and sleeve I! in exeluding dirt and foreign matter from thecasing I.

The propeller shaft 3 is supported by the ballbearings 2| and 22, whichare of a conventional 20] type and are supported by an extension of theThe outer end of the propeller shaft 3 carries the propeller (not shown)and the inner end is formed into a drum 26 on which are mounted clutchplates 21.

The inner end of the power shaft 2 is supported within the drum 2G by abearing 28 of a conventional type. Secured integrally to the shaft 2 atthis end-is a face plate 23 to which is bolted a clutch casing 30 havingmounted within a set 30 of clutch plates '3l which cooperate as shownwith the other clutch plates 21. Mounted on the face plate 23 are theusual piston chambers 36 with pistons 38 to which pressure is applied inactuating the clutch mechanism. Pressure on a piston head 33 drives apiston rod 31 inward. compressing the two sets of clutch plates 21 and3| into frictional engagement, causing the shafts 2 and 3 to rotateintegrally. The forward end of the clutch casing 30 is formed into thesleeve 40 6 and fitted with a bearing 40 to receive a portion of thepropeller shaft 3 as a journal. Within the two shafts 2 and 3 is fitteda core 43 having a bore or pressure line 44 running longitudinallytherethrough. This core 43 secured to the power 45 shaft 2 revolvesfreely within the propeller shaft 3 on journals formed at 45 and 46. Oneend of the pressure line 44 is connected to the piston chamber 36through an opening 41 in the shaft 2 and the pipe 48. The other end ofthe pressure line 44 is connected to the source of pressure supplythrough the opening 49 in the shaft 3, and annular cavity 50 in abearing 53 which, is connected to a control valve 54 by a. pressure line55 bored in the casing I. The pressure sup- 55 ply which is not shown isconnected to the control valve 54. A bore or passage 56 in the core 43is used to supply oil to the bearing as in the usual types oflubricating systems.

The first set of cluster gears comprises three gears ll journaled inball-bearings 58 supported in extensions of the casing I. The gears I Iall mesh with the driving gear 5 which is smaller than the gears II, asclearly appears in Fig. 11 of the drawings. The ratio between thesegears II and 5 reduces the speed the desired amount. Each of these threegears l I has an inner wheel 59 on which the gear I I can revolve, theinner wheel 59 being keyed to a shaft 60 by a key 6|. In the peripheryof each inner wheel 59 are four recesses 63 having wedging faces 64 andnon-wedging faces 65, at right angles thereto. shape of the recesses 63and the relationship of the wedging faces 64 and non-wedging faces 65are such that a wedging element or wedging roller 66 inserted in thespace between the inner wheel 59 and the gear ll formed by the recess 63will bind the inner wheel 59 to the-gear ll when the roller 66 is forcedto one end'of the recess 63 and allow the gear H to revolve freely onthe inn er wheel59 when the roller 66 is forced to the other end of therecess 63. For these purposes, a non-wedging face 65 is also provided toprevent the face 65 and to allow the roller 66 to revolve as a rollerhearing. The non-wedging face 65 extends perpendicularly to a tangent atthe point where the non-wedging face 65joins the periphery of the innerwheel 59, but this angle may be varied so long as it is suflicientlyobtuse that wedging action is avoided. By the same reasoning the wedgingface 66 must depart considerably from a line perpendicular to a tangentdrawn to the point where the wedging face 64 joins the periphery of theinner wheel 59.

Considering the important characteristics of the recesses 63 fromanother viewpoint, the nonwedging face must make a. sufiiciently obtuseangle with the segment 61 of the are formed by the inner surface of gearI I as spanned by the recess 63, that the roller 66 will not wedge andbind the gear H to the inner wheel 59. The wedging face 64 mustmake-asufllciently acute angle with this same segment of arc that the roller66 will be wedged between the gear H and inner wheel 59 binding themintegrally.

. As the rollers 66 are to rotate, as in roller bear- I ings, when thegear II and inner wheel 59 are free, the bearing pieces 69 are insetinto the surface of the wedging faces 64 to take this wear and are of ametal appropriate to their function.

Formed integrally on the shafts 60 are gears I0 comprising the secondset of cluster gears 8 and all meshing with the driven gear 9 which iskeyed to the propeller shaft 3 by the key II. These gears 10 and 9 areof 1:1 ratio, the .reduction taking place in the ratio of gears I l todriving gear 5.

.Of course, the reduction in speed by varying the various ratios hasmany possibilities well understood in the art.

In describing the operation of this invention, it

will first be assumed that the aeroplane is on the The driving gear5'formed integrally with sleeve to rotate as one.

The size and.

6, drives .the gears II comprising the first set of cluster gears I. Thegears ll urge the rollers 66 into the acute angle formed by the wedgingfaces 64 and the subtended arcuate segments 61 of the inner surfaces ofsaid gears II thereby wedging 5 each inner wheel 59 and itscorresponding gear 5 I As the gears I l-are larger than the driving gear5, the reduction in speed is ac-,- complished by this gear ratio. Thegears H revolvingintegrally with inner wheels 59 now cause 10 reducedspeed through meshing with the driven 15 gear 9 which is of the samesize as the gears I6.

The engine is thus driving the propeller at a reduced speed through thereduction gear described. After the aeroplane has left the ground ahigher speed is desired and this is obtained by putting 20 pressure onthe clutch by operating the valve 54 which'causes the pistons 36 topress the interacting clutch plates 21 and 3| into frictionalengagement. The power shaft 2 and the propeller shaft 3 are now boundtogether and turning as one shaft thus connecting the propeller directlyto the engine. The effect of this on the reduction gear train is thatthe second set of cluster gears 8 are now driven faster than the firstset I and these two sets of gears i and 8 must be freed from each other.This is accomplished through the overriding clutch mechanism l9 fittedto the first setof cluster gears l. The inner wheels 59 now turn fasterthan the gears i I and the wedge rollers 66 are rolled to the largerends of the recesses and into contact with the non-wedging faces 65 andbearing pieces 69 where these rollers 66 function as roller bearings andallow the gears ll to turn on the inner wheels 59. The aeroplane is nowrunning with propeller directly connected to 60 motor and hence with anincreased speed limit.

It is noted that the propeller speed was thus changed without freeingthe engine and propeller .from each other and there was a constanttorque at all times through the transmission drive. One ll speed simplymerges into the other without any interim freedom of propeller fromengine. The advantages andbenefits seem clear in thus eliminating theusual interim of disconnection of motor and propeller during changes ofspeed. 66

The aeroplane is always driven by either one or the other speeds andthere is no question of falling betweenthe two and permitting the engineto race without. load. Further, the mechanism by which these benefitsare obtained is character- 55 ized by its mechanical simplicity, ease ofoperation and the absence of easily worn or breakable parts.

While my invention has been described in some detail with reference to aspecific embodiment,

various changes in the form of apparatus used are within thecontemplation of the invention and such changes should not be deemed toconstitute a departure from the spirit of the invention as hereinafterclaimed.

Having thus describedmy invention, I claim:

A constant torque multiple speed transmission for aircrafts, comprisinga casing with shaft supporting bearing, a hollow power shaft, a hollowpropeller shaft, a clutch casing keyed to the driv- 7 ing shaft havingclutch plates mounted on the inside thereof, a second set of clutchplates mounted on the driven shaft, the plates of 'one set extendingbetween the plates of the other set,

a reduction gear connecting said clutch casing with said driven shaft,one of said gears having an overriding clutch mechanism automaticallydisengaging said gear from its shaft, when said clutch is engaged,pressure meansior actuating said clutch, a core integrally securedwithin said power shaft and having journals for riding on the innersurface of said propeller shait, an annular cavity iormed in the shaftsupporting bearing in line with one of said core journals and connectedto a pressure source through a control valve, and a pressure line insaid core connecting said annulaicavity to said pressure means foractuating 5 said clutch.

ALBERT R. JACOBS.

